MRI protocol for diagnosing pediatric appendicitis
Magnetic resonance imaging (MRI) is recommended in cases of suspected appendicitis in children when ultrasound is non-diagnostic or equivocal, but there is no uniformly accepted protocol for MRI in this indication. Radiologists at the New York University School of Medicine recently compared a single contrast-enhanced gradient recalled echo sequence (radial GRE) to two other protocols using multiple sequences, and found it comparable and acceptable, according to their article in the Feb.19, 2019 Pediatric Radiology.
Shailee V. Lala, MD, and colleagues compared a single contrast-enhanced radial GRE sequence with contrast-enhanced 3-D GRE, and a multi-sequence, multi-planar MRI examination that included contrast-enhanced radial GRE of patients with normal appendixes. Their patient cohort consisted of 93 patients between ages 7 and 18 who underwent 96 MRI examinations. All exams included an axial 3D GRE, an axial radial GRE, and coronal single-shot fast spin echo.
The authors created three data sets from each examination which included axial radial GRE images only, axial 3-D GRE images only, and multi-planar, multi-sequential images that included axial radial GRE. Two radiologists reviewed the data sets separately, noting the level of visualization of the appendix and rating their degree of confidence in the visualization for each.
They found the appendix to be fully visualized in 59% of the multi-sequential image set, 56% in the radial GRE alone image set, and 28% in the axial 3-D GRE image set. Partial appendix visualization was 81%, 76%, and 57% respectively. The authors said that when the appendix was at least partially visualized with multi-sequential assessment, it was seen more often on radial GRE than on coronal single-shot fast spin echo.
The confidence level for the multi-sequential image set based on a 5-point Likert score was 3.82 for multi-sequential assessment compared to 3.73 for the radial GRE alone.
The findings suggest the radial GRE sequence can yield high diagnostic accuracy, and that it allows detection of the normal appendix at rates similar to that of multi-sequence assessment. The authors suggest that a radial GRE sequence be considered for a brief, high-yield protocol for suspected appendicitis in children. They also recommend a limited protocol, to include coronal and axial single-shot fast spin echo (SSFSE) or T2-weighted fat-saturated FSE, in addition to radial GRE, for a targeted assessment of suspected appendicitis.
REFERENCE
- Lala SV, Strubel N, Nocera N, et al. Visualization of the normal appendis in children: feasibility of a single contrast-enhanced radial gradient recalled echo MRI sequence. Pediatr Radiol. Published online February 19, 2019. doi: 10.1007/s00247-019-04352-1.